What's A State Within A State?

I see that the Washington Post has a nuanced view of the Iranian Revolutionary Guards Corps:

…the Revolutionary Guard, a radical state within Iran's Islamic state, is waging war against the United States and trying to kill as many American soldiers as possible.

Which smells suspiciously as if some editorialist is trying to reserve judgment on “Iran’s Islamic State,” as if we could fight the Revolutionary Guards but make nice to the regime. Kinda like the old days when some Communists would say “if only Stalin knew the terrible things the KGB is up to, he’d fix it.”

Exactly. That it is even possible for some to conflate the Islamic Revolutionary Guard Corps with some fictitious autonomous zone operating beyond the control of the regime it serves is precisely one of the reasons why I argue against declaring the IRGC and/or its Quds Force a terrorist entity(s) separate from the regime.

Imagine twenty years ago declaring war on the Soviet Marines. We, of course, had no quarrel with the Soviet Navy or its Red Army.

Yes. I understand the nuances of state sponsorship of terrorism. I also think they're uneccessary.